Set this in the File > File Info dialog. See the Online Help: https://helpx.adobe.com/indesign/using/saving-documents.html#work_with_metadata
Strangely enough, some of the items in this dialog do not appear in the regular PDF "Document Properties" dialog ('author title', 'copyright notice'), and some of them are known to misbehave ('keywords'). But Title and Author work just fine.
But every time enter the information.
I've tried in the / files / file information / can be done, but each must be entered to open a new file.
Q: Do you have other methods?
Use Adobe Bridge, setup the creator field in a metadata template and then apply this template to multiple selected files (be careful and work on duplicates of original files unless you are sure that you know what you are doing, as it is easy to mess up your metadata).